Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2012

Long-term Debt, Unclassified [Abstract]

Long-term Debt Outstanding

Maturity Year	Description	Interest Rate	2012			2011
2012	Secured Medium-Term Notes	7.37%	$	—		$	7,000
2013	First Mortgage Bonds	1.68%	50,000			50,000
2018	First Mortgage Bonds	5.95%	250,000			250,000
2018	Secured Medium-Term Notes	7.39%-7.45%	22,500			22,500
2019	First Mortgage Bonds	5.45%	90,000			90,000
2020	First Mortgage Bonds	3.89%	52,000			52,000
2022	First Mortgage Bonds	5.13%	250,000			250,000
2023	Secured Medium-Term Notes	7.18%-7.54%	13,500			13,500
2028	Secured Medium-Term Notes	6.37%	25,000			25,000
2032	Secured Pollution Control Bonds (1)	(1)	66,700			66,700
2034	Secured Pollution Control Bonds (2)	(2)	17,000			17,000
2035	First Mortgage Bonds	6.25%	150,000			150,000
2037	First Mortgage Bonds	5.70%	150,000			150,000
2040	First Mortgage Bonds	5.55%	35,000			35,000
2041	First Mortgage Bonds	4.45%	85,000			85,000
2047	First Mortgage Bonds (3)	4.23%	80,000			—
	Total secured long-term debt		1,336,700			1,263,700
2023	Unsecured Pollution Control Bonds	6.00%	—			4,100
	Other long-term debt and capital leases		5,092			5,455
	Settled interest rate swaps		(27,900		)	(10,629		)
	Unamortized debt discount		(1,453		)	(1,626		)
	Total		1,312,439			1,261,000
	Secured Pollution Control Bonds held by Avista Corporation (1) (2)		(83,700		)	(83,700		)
	Current portion of long-term debt		(50,372		)	(7,474		)
	Total long-term debt		$	1,178,367		$	1,169,826

(1) In December 2010, $66.7 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due 2032, which had been held by Avista Corp. since 2008, were refunded by a new bond issue (Series 2010A). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, these bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Consolidated Balance Sheet.

(2) In December 2010, $17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds, (Avista Corporation Colstrip Project) due 2034, which had been held by Avista Corp. since 2009, were refunded by a new bond issue (Series 2010B). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, the bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Consolidated Balance Sheet.

(3) In November 2012, the Company issued $80.0 million of 4.23 percent First Mortgage Bonds due in 2047.

Long-term Debt Maturities

	2013		2014		2015		2016		2017		Thereafter		Total
Debt maturities	$	50,000	$	—	$	—	$	—	$	—	$	1,254,547	$	1,304,547

Nonrecourse Long-term Debt Maturities

	2013		2014		2015		2016		Total
Debt maturities	$	14,965	$	16,407	$	1,431	$	—	$	32,803